178 SLFMMAKY OF CURRENT RESEA.RCHES RELATING TO 



Reversal of striation concerns only the deeply staining substance of the 

 dark disc, not at all the phenomenon of anisotropy. The contraction 

 band is a genuine new structure, consisting essentially of the dark 

 staining (chromatic) substances originally segregated within the dark 

 disc of the relaxed fibre. The intercalated discs of striated muscle 

 (cardiac and skeletal) are essentially modified irreversible contraction 

 bands. J. A. T. 



Shape of Hive-bees' Cell. — G. Cesaro {Bull. Acad. Roy. Belgique, 

 l'J20, 109-15, 2 figs.). The cell is a rhombododecahedron of which 

 three surfaces form the apex, and six surfaces, parallel to a diagonal of 

 the cube (a diagonal which is the axis of the cell), form the hexagonal 

 body ; the rhombododecahedron is cut by an octahedral surface normal 

 to the axis and forming the hexagonal base. The cell corresponds not 

 only to minimum of surface but to a minimum of perimeter. J. A. T. 



Action of Centrifugal Force on Silkworms. — Hugues Clement 

 {Comptes Rendus Soc. Biol, 1920, 83, 1045-6). It is found that 

 centrifuging considerably retards (for about a month) the onset of 

 the pupal metamorphosis, which normally sets in five or six days after 

 the commencement of the cocoon. J. A. T. 



Circulation in Sphinx convolvuli.— F. Brocher {Arch. Zool. 

 Exper., 1920, 60, 1-45, 20 figs.). The blood circulates in the body of 

 this moth as the result of two aspiratory forces. The activity of the 

 dorsal vessel draws the blood into the abdomen. The activity of the 

 thoracic pulsatile organs pumps the blood into the currents produced 

 by the dorsal vessels and makes it circulate in the wings, .the legs, and 

 the muscles of the thorax. The pulsatile thoracic organs have been 

 found by Brocher in all orders of insects except Hemiptera. But in 

 the Hemiptera there are special pulsatile organs in the legs. In Sphinx 

 convolvuli the pulsatile organ of the mesothorax is very large and it is 

 easy to see it working in the living insect. In the somnolent insect 

 it beats 10 to 12 times in a minute ; in the disturbed insect 75 times ; 

 in the active insect the pulsations are too rapid to be counted. The 

 metatergal pulsatile organ, on the other hand, is very minute, and it 

 does not communicate directly either with the dorsal vessel or with the 

 aorta. In some other insects (ants ?) it is probable that both the 

 mesothoracic and the metatergal pulsatile organs are independent of 

 the dorsal vessel and the aorta. J. A. T. 



Immunity in Caterpillars of Wax-moth. — S. Metalnikow {Comptes 

 Rendus Soc. Biol, 1920, 83, 817-20). The caterpillars of Oalleria 

 meUonella show a remarkable immunity to virulent microbes, such as 

 those of tuberculosis, diphtheria, tetanus and plague, but they are very 

 susceptible to others which are only slightly pathogenic. There is 

 very active phagocytosis, and the phagocytes agglomerate into co-opera- 

 tive capsules. The toxic substances produced by certain microbes set 

 the phagocytic activity agoing, while in other cases, as in the case of 

 saprophytic bacteria and species like Bacillus coli, there is little or no 

 activation. Paillot has made caterpillars of Ayroiis immune to Bacillus 



